I am also new, Level 63. Running Phasma (L), Asajj, Rey, RG and JC. For the first nodes I also run Daka, Boba and Fives. I have won almost every GW since playing, so I have some gold for 5*-Health-Mods, leveling and enough Training Driods and ability mats.
Royal Guard really helps you because of his reliable stun and is great with Phasma lead. I only have him on 3* but he is still really good, always protects injured allies so I can put two healers in the next round if something goes wrong. With intelligent stuns you can beat teams who are stronger than you because the biggest guy is never able to do anything. But I drop fast in Arena because AI cannot play this team nearly as good as me.
For farming, do you want to play rebels, empire, sith, jedi or something else? For the first three teams you need rebels to unlock palpatine (at least five toons with five stars). Therefore Biggs would be good in GW (Team Biggs, Wedge, Ackbar, Lando, STH/Leia). Vader is not very often in fleet store, so just buy him whenever you see him. With all the Empire/Siths on the rise, Rex is probably also a good choice for Fleet store.
Noob question: Can anyone explain me how to retreat GW?